MESOZOIC AND CENOZOIC "CALCISPHERES"- UPDATE IN SYSTEMATICS

Dorothea Janojske and Helmut Keupp
lnstitut jar Palaontologie FU Berlin, Germany
INTRODUCTION
This note outlines the systematic concept used by the working group in Berlin for their research on
Mesozoic and Cenozoic Calcispheresll during the last decade. This research has been supported
mainly by the IIDeutsche Forschungsgemeinschaftll.
Many details and problems of this concept are not discussed here but in the references.
Further discussions, questions and remarks (negative and positive) are expected.
11THE NATURE OF CALCISPHERESIICalcispheresll found in Mesozoic and CenozQic calcareous nannofossil assemblages are mainly theskeletal remains of dinoflagellates. Dinoflagellates can produce various fossilizable remains during
the different stages of their life-cycle.
In general, the life-cycle of dinoflagellates consists of a vegetative stage and a cyst stage.
During the vegetative stage the motile cells are covered by a cellulosic, non fossilizable theca; thereproduction is asexual by mitosis. Before encystment, gametes are produced by mitotic division andafter fusion of the gamete cells the planozygote reduces cell organelles and flagellae. Then encystment
takes place by forming a thick cyst wall of acid-:resistant organic material (sporopollenin ?); only afew living taxa use calcite (Dale 1983, Gao et al. 1989). These cysts are fossilizable, and fossil
remains of dinoflagellates are usually assumed to be cysts. After a period of dormancy meiotic
division and excystment takes place: the vegetative cells leave the cyst through the archaeopyle.
Tangen et al. (1982), Inouye & Pienaar (1983) and Bjornland (1990) found that Ihoracosphaera heimii is an unusual dinoflagellate species with a calcareous shell quring the vegetative stage.
The occurrence of gametes, fusion and encystment has not observed to date. T. heimii is the typespecies of the genus Ihoracosphaera consequently only CalcisphereS which have the same distinctive
wall structure, and which are likely to be shells of the vegetative stage can be placed in this genus.
According to Tangen et al. (1982) the order Thoracosphaerales with until now only one species,
Ihoracosphaera heimii, may be a sister group of the order Peridiniales Haeckel 1894 (Keupp 1991).
All other calcispheres" known and supposed to be calcareous dinoflagellate cysts should beplaced into the family Calciodinellaceae Deflandre 1947 emend. Bujak and Davies 1983.
Most of the calcispheres found in recent sediments have been shown in cultures to be cyst
stages of dinoflagellates (Wall et al 1970, Fiitterer 1976, Montresor & Zingone 1988, Akselman &Keupp 1990, Matsuoka et al. 1990, Lewis 1991). The realization of paratabulation patterns in somefossil calcispheres shows their cyst nature. Paratabulation patterns in calcispheres always belong
to the same orthohexa-formula, which supports the interpretation of the Calciodinellaceae as amonophyletic group (Keupp 1991).
11111111111111SYSTEMATICS
Calcareous dinocysts are divided into three subfamilies based on the crystallographic orientation of
the calcite crystals forming the outer layer of the cyst wall (see figure):
Subfam. Orthopithonelloideae Keupp 1987. C-axes of the calcite crystals perpendicular to cyst
surface.
e.g.: Sphaerodinella ("Ihoracosphaera") albatrosiana (Kamptner 1963) Keupp & Versteegh 1989Subfam. Obliquipithonelloideae Keupp 1987. C-axes of the calcite crystals inclined (oblique totangential) at various angles and directions (even in one specimen).
e.g.: Obliquipithonella ("Ihoracosphaera") operculata (Bramlette & Martini 1964) Fiitterer 1990

14INA Newsletter, 14/1 - 1992

Subfam. Pithonelloideae Keupp 1987. C-axes of the calcite crystals inclined at the same angle andthe same direction to cyst surface.
e.g.: Pithonella sphaerica (Kaufmann 1865) Lorenz 1902

Taxa which show paratabulation patterns are found in all three subfamilies (orthopithonelloid:
Calciodinellum operosum Deflandre 1947, obliquipithonelloid: Bicarinellum eulineatum Keupp 1987,
and pithonelloid: Tetratropsis corbula Willems 1990).

REFERENCES
Akselman R. & Keupp H. 1990: Recent obliquipithonelloid calcareous cysts of Scrippsiella patagonica sp. nov. (Peridiniaceae,Dinophyceae) from plankton of the Golfo San Jorge (Patagonia, Argentina).- Mar. Micropaleont:, 16, 169-179.
Bjornland T. 1990: Chromatographic separation and spectrometric characterization of native carotenoids from the marine
dinoflagellate Thoracosphaera heimi.- Biochem.Syst.Ecol., 18, 307-316.
Dale B. 1983: Dinoflagellate resting cysts: "benthic plankton".- In: Fryxell, G.A. (ed.) "Survival strategies of the algae."
Cambridge University Press, p.69-136.
Gao X., Dodge J .D. & Lewis J. 1989: An ultrastructural study of planozygotes and encystment of a marine dinoflagellate,Scrippsiella sp .. - Br.phycol.J., 24, 53-165.
Flitterer D. 1976: Kalkige Dinoflagellaten ("Calciodinelloideae") und die systematische Stellung der Thoracosphaeroideae.N.Jb. Geol.Palaont:Abh., 151, 119-141.
Flitterer D.K. 1990: Distribution of calcareous dinoflagellates at the Cretaceous-Tertiary boundary of Queen Maud Rise,
Eastern Weddell Sea, Antarctica (ODP Leg 113).- In: Barker, P.F., Kennett, J.P. et al., Proc.ODP Sci.Res., 113:
College Station, TX (Ocean Drilling Programm), 533-548.
Inouye I. & Pienaar R.N. 1983: Observations on the life cycle and microanatomy of Thoracosphaera heimi (Dinophyceae) withspecial reference to its systematic position.- S.Afr.J.Bot. 1983, 2, 63-75.
Keupp H. 1987: Die kalkigen Dinoflagellatenzysten des Mittelalb his Untercenoman von Escalles/Boulonnais (N-Frankreich).Facies, 16, 37-88.
Keupp H. & Versteegh G. 1989: Ein neues systematisches Konzept ffir kalk.ige Dinoflagellaten-Zysten der Subfamilie
Orthopithonelloideae Keupp 1987.- Berliner geowiss.Abh., A, 106, 207-219.
Keupp H. 1991: Fossil calcareous dinoflagellates cysts.- In: Riding R. (ed.)" Calcareous algae and stromatolites."- Springer,
p. 267-286.
Lewis J. 1990: Cyst-theca relationships in Scrippsiella (Dinophyceae) and related orthoperidinoid genera.- Botanica marina,34, 91-106.
Matsuoka K., Kobayashi A. & Gains G. 1990: A new species of the genus Ensiculifera (Dinophyceae): its cyst and motileforms.- Bull.PlankJon Soc.Jpn, 37, 127-144.
Montresor M. & Zingone A. 1988: Scrippsiella precaria sp. nov. (Dinophyceae), a marine dinoflagellate from the Gulf ofNaples.- Phycologia, 27, 387-394.
Tangen K., Brand L.E., Blackwelder P.L. & Guillard R.R.L. 1982: Thoracosphaera heimi (Lohmann) Kamptner is adinophyte: observations on its morphology and life cycle.- Mar. Micropaleont., 1, 193-212.
Wall D., Guillar, R.R.L. Dale B., Swift E. & Watabe N. 1970: Calcitic resting cysts in Peridinium trochoideum (Stein)
Lemmermann, an autotrophic marine dinoflagellate.- Phycologia, 9, 151-156.
Willems H. 1990: Tetratropsis, eine neue Kalkdinoflagellaten-Gattung (Pithonelloideae) aus der Ober-Kreide von Liigerdorf(N-Deutschland).- Senckenbergiana leth., 70, 239-257.

INA Newsletter, 14/1 - 1992

15

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